The neural basis of morality: not just where, but when.

The neural basis of morality: not just where, but when We have known for some time that an intact ventromedial pre-frontal cortex (PFC) is essential for normal social and moral functioning , thanks in large part to studies of individuals who have suffered damage to it (Damasio, 1994). In this issue of Brain, Taber-Thomas and colleagues report that the specific nature of a person's moral impairment depends not only upon where brain damage occurs, but also when (Taber-Thomas et al., 2014). Their point of departure is a landmark study showing that individuals with damage to ventromedial PFC make abnormal judgements when faced with a specific class of moral dilemma (Koenigs et al., 2007). These dilemmas hinge on a trade-off between allowing several people to die, or saving them by personally killing a single victim. For instance, the trolley problem asks whether it is acceptable to save five people from being hit by a runaway trolley by shoving a man in front of it in order to slow it down (such a bizarrely unfortunate railway mishap may seem the stuff of pure fantasy, but try telling that to Phineas Gage). Koenigs and colleagues (2007) showed that although neuroty-pical individuals and those with brain damage to regions outside the ventromedial PFC tended to disfavour such direct harm despite its utilitarian benefits, individuals with adult-onset damage to ventromedial PFC are significantly more likely to judge such harms acceptable. Importantly, however, the differences between groups did not extend to another class of moral 'dilemma'. Specifically, ventromedial PFC participants were just as likely as others to condemn self-interested harmful actions (bumping off a stingy boss, stealing a wallet, selling a daughter into the pornography industry, and so forth). The ventromedial PFC is widely considered to play a role in bringing affect to bear on decision-making processes (Grabenhorst and Rolls, 2011), and recent research emphasizes a key role of affect in moral judgement (Haidt, 2012; Greene, 2013). Koenigs and colleagues therefore concluded that ventro-medial PFC damage likely interfered with the typical aversive af-fective response to harmful actions, thus biasing moral decisions. By contrast, they argued, participants were able to draw on explicit knowledge of the norm against harming in self-interest to deliver typical judgements of the cases that lacked a utilitarian rationale. Taber-Thomas and colleagues replicated this experiment with the addition of a key new group: eight individuals who suffered damage to ventromedial PFC during childhood. …